Two plate reverse firing electromagnetic ink jet printing mechanism

ABSTRACT

An ink jet print head uses a static plate and a movable plate to eject ink. A fixed electric copper coil is located within a nozzle chamber. The movable plate has an embedded electric coil located close to a fixed electric coil such that when a current passing through the coils is altered, the movable plate moves towards or away from the fixed plate. This movement causes ejection of ink from the nozzle chamber via an ink ejection port. A torsional spring is connected to the movable plate and the movable plate goes from a quiescent position to a spring loaded position upon activation of the coils. Upon deactivation of the coils the spring causes the movable coil to return to its quiescent position and to eject ink. The coils can have a stacked multi-level spiral of conductive material interconnected at a central axial point of the spiral.

CROSS REFERENCES TO RELATED APPLICATIONS

The following Australian provisional patent applications are herebyincorporated by cross-reference. For the purposes of location andidentification, U.S. patent applications identified by their U.S. patentapplication serial numbers (U.S. Ser. No.) are listed alongside theAustralian applications from which the U.S. patent applications claimthe right of priority.

US PATENT APPLICATION (CLAIMING CROSS-REFERENCED RIGHT OF PRIORITYAUSTRALIAN FROM AUSTRALIAN PROVISIONAL PROVISIONAL PATENT NO.APPLICATION) DOCKET NO. PO7991 09/113,060 ART01 PO8505 09/113,070 ART02PO7988 09/113,073 ART03 PO9395 09/112,748 ART04 PO8017 09/112,747 ART06PO8014 09/112,776 ART07 PO8025 09/112,750 ART08 PO8032 09/112,746 ART09PO7999 09/112,743 ART10 PO7998 09/112,742 ART11 PO8031 09/112,741 ART12PO8030 09/112,740 ART13 PO7997 09/112,739 ART15 PO7979 09/113,053 ART16PO8015 09/112,738 ART17 PO7978 09/113,067 ART18 PO7982 09/113,063 ART19PO7989 09/113,069 ART20 PO8019 09/112,744 ART21 PO7980 09/113,058 ART22PO8018 09/112,777 ART24 PO7938 09/113,224 ART25 PO8016 09/112,804 ART26PO8024 09/112,805 ART27 PO7940 09/113,072 ART28 PO7939 09/112,785 ART29PO8501 09/112,797 ART30 PO8500 09/112,796 ART31 PO7987 09/113,071 ART32PO8022 09/112,824 ART33 PO8497 09/113,090 ART34 PO8020 09/112,823 ART38PO8023 09/113,222 ART39 PO8504 09/112,786 ART42 PO8000 09/113,051 ART43PO7977 09/112,782 ART44 PO7934 09/113,056 ART45 PO7990 09/113,059 ART46PO8499 09/113,091 ART47 PO8502 09/112,753 ART48 PO7981 09/113,055 ART50PO7986 09/113,057 ART51 PO7983 09/113,054 ART52 PO8026 09/112,752 ART53PO8027 09/112,759 ART54 PO8028 09/112,757 ART56 PO9394 09/112,758 ART57PO9396 09/113,107 ART58 PO9397 09/112,829 ART59 PO9398 09/112,792 ART60PO9399 09/112,791 ART61 PO9400 09/112,790 ART62 PO9401 09/112,789 ART63PO9402 09/112,788 ART64 PO9403 09/112,795 ART65 PO9405 09/112,749 ART66PP0959 09/112,784 ART68 PP1397 09/112,783 ART69 PP2370 09/112,781 DOT01PP2371 09/113,052 DOT02 PO8003 09/112,834 Fluid01 PO8005 09/113,103Fluid02 PO9404 09/113,101 Fluid03 PO8066 09/112,751 IJ01 PO807209/112,787 IJ02 PO8040 09/112,802 IJ03 PO8071 09/112,803 IJ04 PO804709/113,097 IJ05 PO8035 09/113,099 IJ06 PO8044 09/113,084 IJ07 PO806309/113,066 IJ08 PO8057 09/112,778 IJ09 PO8056 09/112,779 IJ10 PO806909/113,077 IJ11 PO8049 09/113,061 IJ12 PO8036 09/112,818 IJ13 PO804809/112,816 IJ14 PO8070 09/112,772 IJ15 PO8067 09/112,819 IJ16 PO800109/112,815 IJ17 PO8038 09/113,096 IJ18 PO8033 09/113,068 IJ19 PO800209/113,095 IJ20 PO8068 09/112,808 IJ21 PO8062 09/112,809 IJ22 PO803409/112,780 IJ23 PO8039 09/113,083 IJ24 PO8041 09/113,121 IJ25 PO800409/113,122 IJ26 PO8037 09/112,793 IJ27 PO8043 09/112,794 IJ28 PO804209/113,128 IJ29 PO8064 09/113,127 IJ30 PO9389 09/112,756 IJ31 PO939109/112,755 IJ32 PP0888 09/112,754 IJ33 PP0891 09/112,811 IJ34 PP089009/112,812 IJ35 PP0873 09/112,813 IJ36 PP0993 09/112,814 IJ37 PP089009/112,764 IJ38 PP1398 09/112,765 IJ39 PP2592 09/112,767 IJ40 PP259309/112,768 IJ41 PP3991 09/112,807 IJ42 PP3987 09/112,806 IJ43 PP398509/112,820 IJ44 PP3983 09/112,821 IJ45 PO7935 09/112,822 IJM01 PO793609/112,825 IJM02 PO7937 09/112,826 IJM03 PO8061 09/112,827 IJM04 PO805409/112,828 IJM05 PO8065 09/113,111 IJM06 PO8055 09/113,108 IJM07 PO805309/113,109 IJM08 PO8078 09/113,123 IJM09 PO7933 09/113,114 IJM10 PO795009/113,115 IJM11 PO7949 09/113,129 IJM12 PO8060 09/113,124 IJM13 PO805909/113,125 IJM14 PO8073 09/113,126 IJM15 PO8076 09/113,119 IJM16 PO807509/113,120 IJM17 PO8079 09/113,221 IJM18 PO8050 09/113,116 IJM19 PO805209/113,118 IJM20 PO7948 09/113,117 IJM21 PO7951 09/113,113 IJM22 PO807409/113,130 IJM23 PO7941 09/113,110 IJM24 PO8077 09/113,112 IJM25 PO805809/113,087 IJM26 PO8051 09/113,074 IJM27 PO8045 09/113,089 IJM28 PO795209/113,088 IJM29 PO8046 09/112,771 IJM30 PO9390 09/112,769 IJM31 PO939209/112,770 IJM32 PP0889 09/112,798 IJM35 PP0887 09/112,801 IJM36 PP088209/112,800 IJM37 PP0874 09/112,799 IJM38 PP1396 09/113,098 IJM39 PP398909/112,833 IJM40 PP2591 09/112,832 IJM41 PP3990 09/112,831 IJM42 PP398609/112,830 IJM43 PP3984 09/112,836 IJM44 PP3982 09/112,835 IJM45 PP089509/113,102 IR01 PP0870 09/113,106 IR02 PP0869 09/113,105 IR04 PP088709/113,104 IR05 PP0885 09/112,810 IR06 PP0884 09/112,766 IR10 PP088609/113,085 IR12 PP0871 09/113,086 IR13 PP0876 09/113,094 IR14 PP087709/112,760 IR16 PP0878 09/112,773 IR17 PP0879 09/112,774 IR18 PP088309/112,775 IR19 PP0880 09/112,745 IR20 PP0881 09/113,092 IR21 PO800609/113,100 MEMS02 PO8007 09/113,093 MEMS03 PO8008 09/113,062 MEMS04PO8010 09/113,064 MEMS05 PO8011 09/113,082 MEMS06 PO7947 09/113,081MEMS07 PO7944 09/113,080 MEMS09 PO7946 09/113,079 MEMS10 PO939309/113,065 MEMS11 PP0875 09/113,078 MEMS12 PP0894 09/113,075 MEMS13

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE INVENTION

The present invention relates to ink jet printing and in particulardiscloses a two plate reverse firing electromagnetic ink jet printer.

The present invention further relates to the field of drop on demand inkjet printing.

BACKGROUND OF THE INVENTION

Many different types of printing have been invented, a large number ofwhich are presently in use. The known forms of print have a variety ofmethods for marking the print media with a relevant marking media.Commonly used forms of printing include offset printing, laser printingand copying devices, dot matrix type impact printers, thermal paperprinters, film recorders, thermal wax printers, dye sublimation printersand ink jet printers both of the drop on demand and continuous flowtype. Each type of printer has its own advantages and problems whenconsidering cost, speed, quality, reliability, simplicity ofconstruction and operation etc.

In recent years, the field of ink jet printing, wherein each individualpixel of ink is derived from one or more ink nozzles has becomeincreasingly popular primarily due to its inexpensive and versatilenature.

Many different techniques on ink jet printing have been invented. For asurvey of the field, reference is made to an article by J Moore,“Non-Impact Printing: Introduction and Historical Perspective”, OutputHard Copy Devices, Editors R Dubeck and S Sherr, pages 207-220 (1988).

Ink Jet printers themselves come in many different types. Theutilisation of a continuous stream ink in ink jet printing appears todate back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hanselldiscloses a simple form of continuous stream electro-static ink jetprinting.

U.S. Pat. No. 3,596,275 by Sweet also discloses a process of acontinuous ink jet printing including the step wherein the ink jetstream is modulated by a high frequency electro-static field so as tocause drop separation. This technique is still used by severalmanufacturers including Elmjet and Scitex (see also U.S. Pat. No.3,373,437 by Sweet et al).

Piezoelectric ink jet printers are also one form of commonly used inkjet printing device. Piezoelectric systems are disclosed by Kyser et.al. in U.S. Pat. No. 3,946,398 (1970) which uses a diaphragm mode ofoperation, by Zolten in U.S. Pat. No. 3,863,212 (1970) which discloses asqueeze mode of operation of a piezoelectric crystal, Stemme in U.S.Pat. No. 3,747,120 (1972) discloses a bend mode of piezoelectricoperation, Howkins in U.S. Pat. No. 4,459,601 discloses a piezoelectricpush mode actuation of the ink jet stream and Fischbeck in U.S. Pat. No.4,584,590 which discloses a shear mode type of piezoelectric transducerelement.

Recently, thermal ink jet printing has become an extremely popular formof ink jet printing. The ink jet printing techniques include thosedisclosed by Endo et al in GB 2007162 (1979) and Vaught et al in U.S.Pat. No. 4,490,728. Both the aforementioned references disclosed ink jetprinting techniques rely upon the activation of an electrothermalactuator which result in the creation of bubble in a constricted space,such as a nozzle, which thereby causes the ejection of ink from anaperture connected to the confined space onto a relevant print media.Printing devices using the electro-thermal actuator are manufactured bymanufacturers such as Canon and Hewlett Packard.

As can be seen from the foregoing, many different types of printingtechnologies are available. Ideally, a printing technology should have anumber of desirable attributes. These include inexpensive constructionand operation, high speed operation, safe and continuous long termoperation etc. Each technology may have its own advantages anddisadvantages in the areas of cost, speed, quality, reliability, powerusage, simplicity of construction operation, durability and consumables.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an alternative formof ink jet printing including an ink jet nozzle from which the ejectionof ink is activated through the use of a static and movable plate.

In accordance with a first aspect of the present invention there isprovided an ink jet nozzle comprising a nozzle chamber having an inkinjection port at one wall of the chamber, a fixed electric coil locatedwithin the chamber or within a wall of the chamber and a movable plate,in which embedded is an electric coil, located close to the fixedelectric coil such that when the amount of current passing through setcoils are altered, the movable plunger plate undergoes correspondingmovement towards or away from the fixed electric coil and wherein themovement is utilised to inject ink from the nozzle chamber via the inkinjection port.

Further, the ink jet nozzle comprises spring means connected to themovable plate wherein the movable plate goes from a quiescent positionto a spring loaded position upon activation of the coils and upondeactivation of the coils the spring means causes the movable coil toreturn to its quiescent position and to thereby eject ink from the inkejection port. Preferably, the fixed electric coil of the movableplunger plate comprises a stacked multi level spiral of conductivematerial and the stacked conductive material is interconnected at acentral axial point of the spiral. The coils are electrically connectedtogether to form a combined circuit. Further, the spring means comprisestorsional springs attached to the movable coil and a conductive stripecontact to the coils is located within the torsional springs.Advantageously, the coil comprises substantially copper and is formedfrom use of a damascene construction. The nozzle is constructed using asacrificial etch to release the structure of the moveable coil.Preferably, the nozzle chamber includes a series of slots within thewalls of the nozzle chamber so as to allow the supply of ink to thenozzle chamber and an outer surface of the nozzle chamber includes aseries of small etched holes for the etching of any sacrificial layerused in the construction of the ink jet print nozzle.

In accordance with a second aspect of the present invention there isprovided a means of ejecting ink from a nozzle chamber using theelectro-magnetic forces between two coils embedded into place to causemovement of at least one of the plates, the movement further causing theconsequential ejection of ink from the nozzle chamber. Further, theutilisation of electro-magnetic forces comprises using theelectro-magnetic forces between coils embedded into a movable and afixed plate so that the movable plate moves closer to the fixed plate,the movable plate further being connected to a spring which upon themovement, stores energy within the spring such as that upon deactivationof a current through the coil, the spring releases its stored energy tothereby cause the movement of the movable plate so as to cause theejection of ink from the nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of thepresent invention, preferred forms of the invention will now bedescribed, by way of example only, with reference to the accompanyingdrawings which:

FIG. 1 is a cross sectional view of a single ink jet nozzle asconstructed in accordance with the preferred embodiment in its quiescentstate;

FIG. 2 is a cross sectional view of a single ink jet nozzle asconstructed in accordance with the preferred embodiment after reachingits stop position;

FIG. 3 is a cross sectional view of a single ink jet nozzle asconstructed in accordance with the preferred embodiment in the keeperface position;

FIG. 4 is a cross sectional view of a single ink jet nozzle asconstructed in accordance with the preferred embodiment afterde-energising from the keeper level.

FIG. 5 is an exploded perspective view illustrating the construction ofthe preferred embodiment;

FIG. 6 is the cut out topside view of a single ink jet nozzleconstructed in accordance with the preferred embodiment in the keeperlevel;

FIG. 7 provides a legend of the materials indicated in FIGS. 8 to 27;and

FIG. 8 to FIG. 27 illustrate sectional views of the manufacturing stepsin one form of construction of an ink jet printhead nozzle.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

In the preferred embodiment, there is provided an ink jet nozzle andchamber filled with ink. Within said jet nozzle chamber is located astatic coil and a movable coil. When energized, the static and movablecoils are attracted towards one another, loading a spring. The ink dropis ejected from the nozzle when the coils are de-energized. Turn now toFIGS. 1-4, there is illustrated schematically the operation of thepreferred embodiment. In FIG. 1, there is shown a single ink jet nozzlechamber 10 having an ink ejection port 11 and ink meniscus in thisposition 12. Inside the nozzle chamber 10 are located a fixed or staticcoil 14 and a movable coil 15. The arrangement of FIG. 1 illustrates thequiescent state in the ink jet nozzle chamber.

The two coils are then energized resulting in an attraction to oneanother. This results in the movable plate 15 moving towards the staticor fixed plate 14 as illustrated in FIG. 2. As a result of the movement,springs 18,19 are loaded. Additionally, the movement of coil 15 maycause ink to flow out of the chamber 10 in addition to a change in theshape of the meniscus 12. The coils are energized for long enough forthe moving coil 15 to reach its position (approximate two microseconds).The coil currents are then turned to a lower “level” while the nozzlefills. The keeper power can be substantially less than the maximumcurrent level used to move the plate 15 because the magnetic gap betweenthe plates 14 and 15 is at a minimum when the moving coil 15 is at itsstop position. The surface tension on the meniscus 12 inserts a netforce on the ink which results in nozzle refilling as illustrated inFIG. 3. The nozzle refilling replaces the volume of the pistonwithdrawal with ink in a process which should take approximately 100microseconds.

Turning to FIG. 4, the coil current is then turned off and the movablecoil 15 acts as a plunger which is accelerated to its normal position bythe springs 18, 19 as illustrated in FIG. 4. The spring force on theplunger coil 15 will be greatest at the beginning of its stroke andslows as the spring elastic stress falls to zero. As a result, theacceleration of plunger plate 15 is high at the beginning of the strokebut decreases during the stroke resulting in a more uniform ink velocityduring the stroke. The movement plate 15 causes the meniscus to bulgeand break off performing ink drop 20. The plunger coil 15 in turnsettles in its quiescent position until the next drop ejection cycle.

Turning now to FIG. 5, there is illustrated a perspective view of oneform of construction of an ink jet nozzle 10. The ink jet nozzle 10 canbe constructed on a silicon wafer base 22 as part of a large array ofnozzles 10 which can be formed for the purposes of providing a printheadhaving a certain dpi, for example, a 1600 dpi printhead. The printhead10 can be constructed using advanced silicon semi-conductor fabricationand micro machining and micro fabrication process technology. The waferis first processed to include lower level drive circuitry (not shown)before being finished off with a two microns thick layer 22 withappropriate vias for interconnection. Preferably, the CMOS layer caninclude one level of metal for providing basic interconnects. On top ofthe layer 22 is constructed a nitride layer 23 in which is embedded twocoil layers 25 and 26. The coil layers 25, 26 can be embedded within thenitride layer 23 through the utilisation of the well-known dualdamascene process and chemical mechanical planarisation techniques(“Chemical Mechanical Planarisation of Micro Electronic Materials” bySterger Wald et al published 1997 by John Wiley and Sons Inc., New York,N.Y.). The two coils 25,26 are interconnected using a fire at theircentral point and are further connected, by appropriate vias at ends28,29 to the end points 28,29. Similarly, the movable coil can be formedfrom two copper coils 31,32 which are encased within a further nitridelayer 33. The copper coil 31,32 and nitride layer 33 also includetorsional springs 36-39 which are formed so that the top moveable coilhas a stable state away from the bottom fixed coil. Upon passing acurrent through the various copper coils, the top copper coils 31,32 areattracted to the bottom copper coils 25,26 thereby resulting in aloading being placed on the torsional springs 36-39 such that, when thecurrent is turned off, the springs 36-39 act to move the top moveablecoil to its original position. The nozzle chamber can be formed vianitride wall portions e.g. 40,41 having slots between adjacent wallportions. The slots allow for the flow of ink into the chamber asrequired. A top nitride plate 44 is provided to cap the top of theinternals of 10 and to provide in flow channel support. The nozzle plate44 includes a series of holes 45 provided to assist in sacrificialetching of lower level layers. Also provided is the ink injection nozzle11 having a ridge around its side so as to assist in resisting any inflow on to the outside surface of the nozzle 10. The etched throughholes 45 are of much smaller diameter than the nozzle hole 11 and, assuch, surface tension will act to retain the ink within the throughholes of 45 whilst simultaneously the injection of ink from nozzle 11.

As mentioned previously, the various layers of the nozzle 10 can beconstructed in accordance with standard semi-conductor and micromechanical techniques. These techniques utilise the dual damasceneprocess as mentioned earlier in addition to the utilisation ofsacrificial etch layers to provide support for structures which arelater released by means of etching the sacrificial layer.

The ink can be supplied within the nozzle 10 by standard techniques suchas providing ink channels along the side of the wafer so as to allow theflow of ink into the area under the surface of nozzle plate 44.Alternatively, ink channel portals can be provided through the wafer bya high density low pressure plasma etch processing system such as thatavailable from surface technology system and known as their AdvancedSilicon Etch (ASE) process. The etched portals 45 being so small thatsurface tension affects not allow the ink to leak out of the smallportal holes. In FIG. 6, there is shown a final assembled ink jet nozzleready for the ejection of ink.

One form of detailed manufacturing process which can be used tofabricate monolithic ink jet print heads operating in accordance withthe principles taught by the present embodiment can proceed by thefollowing steps:

1. Using a double sided polished wafer 22, Complete drive transistors,data distribution, and timing cir-cuits using a 0.5 micron, one poly, 2metal CMOS process 50. This step is shown in FIG. 8. For clarity, thesediagrams may not be to scale, and may not represent a cross sectionthough any single plane of the nozzle. FIG. 7 is a key torepresentations of various materials in these manufacturing diagrams,and those of other cross referenced ink jet configurations.

2. Deposit 0.5 microns of low stress PECVD silicon nitride (Si3N4) 23.The nitride acts as a dielectric, and etch stop, a copper diffusionbarrier, and an ion diffusion barrier. As the speed of operation of theprint head is low, the high dielectric constant of silicon nitride isnot important, so the nitride layer can be thick compared to sub-micronCMOS back-end processes.

3. Etch the nitride layer using Mask 1. This mask defines the contactvias 28,29 from the solenoid coil to the second-level metal contacts.This step is shown in FIG. 9.

4. Deposit 1 micron of PECVD glass 52.

5. Etch the glass down to nitride or second level metal using Mask 2.This mask defines first layer of the fixed solenoid 14. This step isshown in FIG. 10.

6. Deposit a thin barrier layer of Ta or TaN.

7. Deposit a seed layer of copper. Copper is used for its lowresistivity (which results in higher efficiency) and its highelectromigration resistance, which increases reliability at high currentdensities.

8. Electroplate 1 micron of copper 53.

9. Planarize using CMP. Steps 2 to 9 represent a copper dual damasceneprocess. This step is shown in FIG. 11.

10. Deposit 0.5 microns of low stress PECVD silicon nitride 54.

11. Etch the nitride layer using Mask 3. This mask defines the definesthe vias from the second layer to the first layer of the fixed solenoid14. This step is shown in FIG. 12.

12. Deposit 1 micron of PECVD glass 55.

13. Etch the glass down to nitride or copper using Mask 4. This maskdefines second layer of the fixed solenoid 14. This step is shown inFIG. 13.

14. Deposit a thin barrier layer and seed layer.

15. Electroplate 1 micron of copper 56.

16. Planarize using CMP. Steps 10 to 16 represent a second copper dualdamascene process. This step is shown in FIG. 14.

17. Deposit 0.5 microns of low stress PECVD silicon nitride 57.

18. Deposit 0.1 microns of PTFE. This is to hydrophobize the spacebetween the two solenoids 14 m 15, so that when the nozzle 10 fills withink, this space forms an air bubble. The allows the upper solenoid 15 tomove more freely.

19. Deposit 4 microns of sacrificial material. This forms the spacebetween the two solenoids 14,15.

20. Deposit 0.1 microns of low stress PECVD silicon nitride.

21. Etch the nitride layer, the sacrificial layer, the PTFE layer, andthe nitride layer of step 17 using Mask 5. This mask defines the viasfrom the first layer of the moving solenoid 15 to the second layer thefixed solenoid 14. This step is shown in FIG. 15.

22. Deposit 1 micron of PECVD glass 59.

23. Etch the glass down to nitride or copper using Mask 6. This maskdefines first layer of the moving solenoid. This step is shown in FIG.16.

24. Deposit a thin barrier layer and seed layer.

25. Electroplate 1 micron of copper 60.

26. Planarize using CMP. Steps 20 to 26 represent a third copper dualdamascene process. This step is shown in FIG. 17.

27. Deposit 0.1 microns of low stress PECVD silicon nitride 61.

28. Etch the nitride layer using Mask 7. This mask defines the vias fromthe second layer the moving solenoid 15 to the first layer of the movingsolenoid. This step is shown in FIG. 18.

29. Deposit 1 micron of PECVD glass 52.

30. Etch the glass down to nitride or copper using Mask 8. This maskdefines the second layer of the moving solenoid 15. This step is shownin FIG. 19.

31. Deposit a thin barrier layer and seed layer.

32. Electroplate 1 micron of copper 63.

33. Planarize using CMP. Steps 27 to 33 represent a fourth copper dualdamascene process. This step is shown in FIG. 20.

34. Deposit 0.1 microns of low stress PECVD silicon nitride.

35. Etch the nitride using Mask 9. This mask defines the moving solenoid15, including its springs 36-39, and allows the sacrificial material inthe space between the solenoids 14,15 to be etched. It also defines thebond pads. This step is shown in FIG. 21.

36. Wafer probe. All electrical connections are complete at this point,bond pads are accessible, and the chips are not yet separated.

37. Deposit 10 microns of sacrificial material 65.

38. Etch the sacrificial material using Mask 10. This mask defines thenozzle chamber wall 40, 41. This step is shown in FIG. 22.

39. Deposit 3 microns of PECVD glass 66.

40. Etch to a depth of 1 micron using Mask 11. This mask defines thenozzle rim 67. This step is shown in FIG. 23.

41. Etch down to the sacrificial layer using Mask 12. This mask definesthe roof 44 of the nozzle 10 chamber, and the nozzle itself 11. Thisstep is shown in FIG. 24.

42. Back-etch completely through the silicon wafer (with, for example,an ASE Advanced Silicon Etcher from Surface Technology Systems) usingMask 7. This mask defines the ink inlets 68 which are etched through thewafer. The wafer is also diced by this etch. This step is shown in FIG.25.

43. Etch the sacrificial material. The nozzle chambers are cleared, theactuators freed, and the chips are separated by this etch. This step isshown in FIG. 26.

44. Mount the printheads in their packaging, which may be a moldedplastic former incorporating ink channels which supply the appropriatecolor ink to the ink inlets at the back of the wafer.

45. Connect the printheads to their interconnect systems. For a lowprofile connection with minimum disruption of airflow, TAB may be used.Wire bonding may also be used if the printer is to be operated withsufficient clearance to the paper.

46. Hydrophobize the front surface of the printheads.

47. Fill the completed printheads with ink 69 and test them. A fillednozzle is shown in FIG. 27.

It would be appreciated by a person skilled in the art that numerousvariations and/or modifications may be made to the present invention asshown in the specific embodiment without departing from the spirit orscope of the invention as broadly described. The present embodiment is,therefore, to be considered in all respects to be illustrative and notrestrictive.

The presently disclosed ink jet printing technology is potentiallysuited to a wide range of printing systems including: color andmonochrome office printers, short run digital printers, high speeddigital printers, offset press supplemental printers, low cost scanningprinters, high speed pagewidth printers, notebook computers with inbuiltpagewidth printers, portable color and monochrome printers, color andmonochrome copiers, color and monochrome facsimile machines, combinedprinter, facsimile and copying machines, label printers, large formatplotters, photograph copiers, printers for digital photographic‘minilabs’, video printers, PHOTO CD (PHOTO CD is a registered trademark of the Eastman Kodak Company) printers, portable printers for PDAs,wallpaper printers, indoor sign printers, billboard printers, fabricprinters, camera printer.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Ofcourse many different devices could be used. However presently popularink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal ink jet is power consumption.This is approximately 100 times that required for high speed, and stemsfrom the energy-inefficient means of drop ejection. This involves therapid boiling of water to produce a vapor bubble which expels the ink.Water has a very high heat capacity, and must be superheated in thermalink jet applications. This leads to an efficiency of around 0.02%, fromelectricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric ink jet is size andcost. Piezoelectric crystals have a very small deflection at reasonabledrive voltages, and therefore require a large area for each nozzle.Also, each piezoelectric actuator must be connected to its drive circuiton a separate substrate. This is not a significant problem at thecurrent limit of around 300 nozzles per printhead, but is a majorimpediment to the fabrication of pagewidth printheads with 19,200nozzles.

Ideally, the ink jet technologies used meet the stringent requirementsof in-camera digital color printing and other high quality, high speed,low cost printing applications. To meet the requirements of digitalphotography, new ink jet technologies have been created. The targetfeatures include:

low power (less than 10 Watts)

high resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the ink jet systemsdescribed below with differing levels of difficulty. 45 different inkjet technologies have been developed by the Assignee to give a widerange of choices for high volume manufacture. These technologies formpart of separate applications assigned to the present Assignee as setout in the table under the heading Cross References to RelatedApplications.

The ink jet designs shown here are suitable for a wide range of digitalprinting systems, from battery powered one-time use digital cameras,through to desktop and network printers, and through to commercialprinting systems.

For ease of manufacture using standard process equipment, the printheadis designed to be a monolithic 0.5 micron CMOS chip with MEMS postprocessing. For color photographic applications, the printhead is 100 mmlong, with a width which depends upon the ink jet type. The smallestprinthead designed is IJ38, which is 0.35 mm wide, giving a chip area of35 square mm. The printheads each contain 19,200 nozzles plus data andcontrol circuitry.

Ink is supplied to the back of the printhead by injection molded plasticink channels. The molding requires 50 micron features, which can becreated using a lithographically micromachined insert in a standardinjection molding tool. Ink flows through holes etched through the waferto the nozzle chambers fabricated on the front surface of the wafer. Theprinthead is connected to the camera circuitry by tape automatedbonding.

Tables of Drop-on-Demand Ink Jets

Eleven important characteristics of the fundamental operation ofindividual ink jet nozzles have been identified. These characteristicsare largely orthogonal, and so can be elucidated as an elevendimensional matrix. Most of the eleven axes of this matrix includeentries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of inkjet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains36.9 billion possible configurations of ink jet nozzle. While not all ofthe possible combinations result in a viable ink jet technology, manymillion configurations are viable. It is clearly impractical toelucidate all of the possible configurations. Instead, certain ink jettypes have been investigated in detail. These are designated IJ01 toIJ45 above which matches the docket numbers in the table under theheading Cross References to Related Applications.

Other ink jet configurations can readily be derived from these 45examples by substituting alternative configurations along one or more ofthe 11 axes. Most of the IJ01 to IJ45 examples can be made into ink jetprintheads with characteristics superior to any currently available inkjet technology.

Where there are prior art examples known to the inventor, one or more ofthese examples are listed in the examples column of the tables below.The IJ01 to IJ45 series are also listed in the examples column. In somecases, a print technology may be listed more than once in a table, whereit shares characteristics with more than one entry.

Suitable applications for the ink jet technologies include: Homeprinters, Office network printers, Short run digital printers,Commercial print systems, Fabric printers, Pocket printers, Internet WWWprinters, Video printers, Medical imaging, Wide format printers,Notebook PC printers, Fax machines, Industrial printing systems,Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrixare set out in the following tables.

ACTUATOR MECHANISM (APPLIED ONLY TO SELECTED INK DROPS) DescriptionAdvantages Disadvantages Examples Thermal An electrothermal ♦ Largeforce ♦ High power ♦ Canon Bubblejet bubble heater heats the ink togenerated ♦ Ink carrier 1979 Endo et al GB above boiling point, ♦ Simplelimited to water patent 2,007,162 transferring significant construction♦ Low efficiency ♦ Xerox heater-in- heat to the aqueous ♦ No movingparts ♦ High pit 1990 Hawkins et ink. A bubble ♦ Fast operationtemperatures al U.S. Pat. No. 4,899,181 nucleates and quickly ♦ Smallchip area required ♦ Hewlett-Packard forms, expelling the required foractuator ♦ High mechanical TIJ 1982 Vaught et ink. stress. al U.S. Pat.No. 4,490,728 The efficiency of the ♦ Unusual process is low, withmaterials required typically less than ♦ Large drive 0.05% of theelectrical transistors energy being ♦ Cavitation causes transfomaed intoactuator failure kinetic energy of the ♦ Kogation reduces drop. bubbleformation ♦ Large print heads are difficult to fabricate Piezo- Apiezoelectric crystal ♦ Low power ♦ Very large area ♦ Kyser et al U.S.Pat. No. electric such as lead consumption required for actuator3,946,398 lanthanum zirconate ♦ Many ink types ♦ Difficult to ♦ ZoltanU.S. Pat. No. (PZT) is electrically can be used integrate with 3,683,212activated, and either ♦ Fast operation electronics ♦ 1973 Stemmeexpands, shears, or ♦ High efficiency. ♦ High voltage U.S. Pat. No.3,747,120 bends to apply drive transistors ♦ Epson Stylus pressure tothe ink, required ♦ Tektronix ejecting drops. ♦ Full pagewidth ♦ IJ04print heads impractical due to actuator size ♦ Requires electricalpoling in high field strengths during manufacture Electro- An electricfield is ♦ Low power ♦ Low maximum ♦ Seiko Epson, strictive used toactivate consumption strain (approx. Usui et all JP electrostriction in♦ Many ink types 0.01%) 253401/96 relaxor materials such can be used ♦Large area ♦ IJ04 as lead lanthanum ♦ Low thermal required for actuatorzirconate titanate expansion due to low strain (PLZT) or lead ♦ Electricfield ♦ Response speed magnesium niobate strength required is marginal(˜10 (PMN) (approx. 3.5 V/μm) μs) can be generated ♦ High voltagewithout difficulty drive transistors ♦ Does not require requiredelectrical poling ♦ Full pagewidth print heads impractical due toactuator size Ferro- An electric field is ♦ Low power ♦ Difficult to ♦IJ04 electric used to induce a phase consumption integrate withtransition between the ♦ Many ink types electronics antiferroelectric(AFE) can be used ♦ Unusual and ferroelectric (FE) ♦ Fast operationmaterials such as phase. Perovskite (<1 μs) PLZSnT are materials such astin ♦ Relatively high required modified lead longitudinal strain ♦Actuators require lanthanum zirconate ♦ High efficiency a large areatitanate (PLZSnT) ♦ Electric field exhibit large strains of strength ofaround 3 up to 1% associated V/μm can be readily with the AFE to FEprovided phase transition. Electro- Conductive plates are ♦ Low power ♦Difficult to ♦ IJ02, IJ04 static plates separated by a consumptionoperate electrostatic compressible or fluid ♦ Many ink types devices inan dielectric (usually air). can be used aqueous Upon application of a ♦Fast operation environment voltage, the plates ♦ The electrostaticattract each other and actuator will displace ink, causing normally needto be drop ejection. The separated from the conductive plates may ink bein a comb or ♦ Very large area honeycomb structure, required to achieveor stacked to increase high forces the surface area and ♦ High voltagetherefore the force. drive transistors may be required ♦ Full pagewidthprint heads are not competitive due to actuator size Electro- A strongelectric field ♦ Low current ♦ High voltage ♦ 1989 Saito et al, staticpull is applied to the ink, consumption required U.S. Pat. No. 4,799,068on ink whereupon ♦ Low temperature ♦ May be damaged ♦ 1989 Miura et al,electrostatic attraction by sparks due to air U.S. Pat. No. 4,810,954accelerates the ink breakdown ♦ Tone-jet towards the print ♦ Requiredfield medium. strength increases as the drop size decreases ♦ Highvoltage drive transistors required ♦ Electrostatic field attracts dustPermanent An electromagnet ♦ Low power ♦ Complex ♦ IJ07, IJ10 magnetdirectly attracts a consumption fabrication electro- permanent magnet, ♦Many ink types ♦ Permanent magnetic displacing ink and can be usedmagnetic material causing drop ejection. ♦ Fast operation such asNeodymium Rare earth magnets ♦ High efflciency Iron Boron (NdFeB) with afield strength ♦ Easy extension required. around 1 Tesla can be fromsingle nozzles ♦ High local used. Examples are. to pagewidth printcurrents required Samarium Cobalt heads ♦ Copper (SaCo) and magneticmetalization should materials in the be used for long neodymium ironboron electromigration family (NdFeB, lifetime and low NdDyFeBNb,resistivity NdDyFeB, etc) ♦ Pigmented inks are usually infeasible ♦Operating temperature limited to the Curie temperature (around 540 K)Soft A solenoid induced a ♦ Low power ♦ Complex ♦ IJ01, IJ05, IJ08,magnetic magnetic fleld in a soft consumption fabrication IJ10, IJ12,IJ14, core electro- magnetic core or yoke ♦ Many ink types ♦ Materialsnot IJ15, IJ17 magnetic fabricated from a can be used usually present ina ferrous material such ♦ Fast operation CMOS fab such as aselectroplated iron ♦ High efficiency NiFe, CoNiFe, or alloys such asCoNiFe ♦ Easy extension CoFe are required [1], CoFe, or NiFe from singlenozzles ♦ High local alloys. Typically, the to pagewidth print currentsrequired soft magnetic material heads ♦ Copper is in two parts, which ♦metalization should are normally held be used for long apart by aspring. electromigration When the solenoid is lifetime and low actuated,the two parts resistivity attract, displacing the ♦ Electroplating isink. required ♦ High saturation flux density is required (2.0-2.1 T isachievable with CoNiFe [1]) Lorenz The Lorenz force ♦ Low power ♦ Forceacts as a ♦ IJ06, IJ11, IJ13, force acting on a current consumptiontwisting motion IJ16 carrying wire in a ♦ Many ink types ♦ Typically,only a magnetic field is can be used quarter of the utilized. ♦ Fastoperation solenoid length This allows the ♦ High efficiency providesforce in a magnetic field to be ♦ Easy extension useful directionsupplied extermally to from single nozzles ♦ High local the print head,for to pagewidth print currents required example with rare heads ♦Copper earth permanent metalization should magnets. be used for longOnly the current electromigration carrying wire need be lifetime and lowfabricated on the print- resistivity head, simplifying ♦ Pigmented inksmaterials are usualiy requirements. infeasible Magneto- The actuatoruses the ♦ Many ink types ♦ Force acts as a ♦ Fischenbeck, strictiongiant magnetostrictive call be used twisting motion U.S. Pat. No.4,032,929 effect of materials ♦ Fast operation ♦ Unusual ♦ IJ25 such asTerfenol-D (an ♦ Easy extension materials such as alloy of terbium, fromsingle nozzles Terfenol-D are dysprosium and iron to pagewidth printrequired developed at the Naval heads ♦ High local Ordnance Laboratory,♦ High force is currents required hence Ter-Fe-NOL). available ♦ CopperFor best efficiency, the metalization should actuator should be pre- beused for long stressed to approx. 8 electromigration MPa. lifetime andlow resistivity ♦ Pre-stressing may be required Surface Ink underpositive ♦ Low power ♦ Requires ♦ Silverbrook, EP tension pressure isheld in a consumption supplementary force 0771 658 A2 and reductionnozzle by surface ♦ Simple to effect drop related patent tension. Thesurface construction separation applications tension of the ink is ♦ Nounusual ♦ Requires special reduced below the materials required in inksurfactants bubble threshold, fabrication ♦ Speed may be causing the inkto ♦ High efficiency limited by surfactant egress from the ♦ Easyextension properties nozzle. from single nozzles to pagewidth printheads Viscosity The ink viscosity is ♦ Simple ♦ Requires ♦ Silverbrook,EP reduction locally reduced to construction supplementary force 0771658 A2 and select which drops are ♦ No unusual to effect drop relatedpatent to be ejected. A materials required in separation applicationsviscosity reduction can fabrication ♦ Requires special be achieved ♦Easy extension ink viscosity electrothermally with from single nozzlesproperties most inks, but special to pagewidth print ♦ High speed isinks can be engineered heads difficult to achieve for a 100:1 viscosity♦ Requires reduction. oscillating ink pressure ♦ A high temperaturedifference (typically 80 degrees) is required Acoustic An acoustic waveis ♦ Can operate ♦ Complex drive ♦ 1993 Hadimioglu generated and withouta nozzle circuitry et al, EUP 550,192 focussed upon the plate ♦ Complex♦ 1993 Elrod et al, drop ejection region. fabrication EUP 572,220 ♦ Lowefficiency ♦ Poor control of drop position ♦ Poor control of drop volumeThermo- An actuator which ♦ Low power ♦ Efficient aqueous ♦ IJ03, IJ09,IJ17, elastic bend relies upon differential consumption operationrequires a IJ18, IJ19, IJ20, actuator thermal expansion ♦ Many ink typesthermal insulator on IJ21, IJ22, IJ23, upon Joule heating is can be usedthe hot side IJ24, IJ27, IJ28, used. ♦ Simple planar ♦ Corrosion IJ29,IJ30, IJ31, fabrication prevention can be IJ32, IJ33, IJ34, ♦ Small chiparea difficult IJ35, IJ36, IJ37, required for each ♦ Pigmented inks IJ38,IJ39, IJ40, actuator may be infeasible, IJ41 ♦ Fast operation aspigment particles ♦ High efficiency may jam the bend ♦ CMOS actuatorcompatible voltages and currents ♦ Standard MEMS processes can be used ♦Easy extension from single nozzles to pagewidth print heads High CTE Amaterial with a very ♦ High force can ♦ Requires special ♦ IJ09, IJ17,IJ18, thermo- high coefficient of be generated material (e.g. PTFE)IJ20, IJ21, IJ22, elastic thermal expansion ♦ Three methods of ♦Requires a PTFE IJ23, IJ24, IJ27, actuator (CTE) such as PTFE depositionare deposition process, IJ28, IJ29, IJ30, polytetrafluoroethylene underdevelopment: which is not yet IJ31, IJ42, IJ43, (PTFE) is used. Aschemical vapor standard in ULSI IJ44 high CTE materials deposition(CVD), fabs are usually non- spin coating, and ♦ PTFE depositionconductive, a heater evaporation cannot be followed fabricated from a ♦PTFE is a with high conductive material is candidate for low temperature(above incorporated. A 50 μm dielectric constant 350° C.) processinglong PTFE bend insulation in ULSI ♦ Pigmented inks actuator with ♦ Verylow power may be infeasible, polysilicon heater and consumption aspigment particles 15 mW power input ♦ Many ink types may jam the bendcan provide 180 μN can be used actuator force and 10 μm ♦ Simple planardeflection. Actuator fabrication motions include: ♦ Small chip area Bendrequired for each Push actuator Buckle ♦ Fast operation Rotate ♦ Highefficiency ♦ CMOS compatible voltages and currents ♦ Easy extension fromsingle nozzles to pagewidth print heads Conductive A polymer with a high♦ High force can ♦ Requires special ♦ IJ24 polymer coefficient ofthermal be generated materials thermo- expansion (such as ♦ Very lowpower development (High elastic PJTE) is doped with consumption CTEconductive actuator conducting substances ♦ Many ink types polymer) toincrease its can be used ♦ Requires a PTFE conductivity to about 3 ♦Simple planar deposition process, orders of magnitude fabrication whichis not yet below that of copper. ♦ Small chip area standard in ULSI Theconducting required for each fabs polymer expands actuator PTFEdeposition when resistively ♦ Fast operation cannot be followed heated.♦ High efficiency with high Examples of ♦ CMOS temperature (aboveconducting dopants compatible voltages 350° C.) processing include: andcurrents ♦ Evaporation and Carbon nanotubes ♦ Easy extension CVDdeposition Metal fibers from single nozzles techniques cannot Conductivepolymers to pagewidth print be used such as doped heads ♦ Pigmented inkspolythiophene may be infeasible, Carbon granules as pigment particlesmay jam the bend actuator Shape A shape memory alloy ♦ High force is ♦Fatigue limits ♦ IJ26 memory such as TiNi (also available (stressesmaximum number alloy known as Nitinol - of hundreds of MPa) of cyclesNickel Titanium alloy ♦ Large strain is ♦ Low strain (1%) developed atthe Naval available (more than is required to extend OrdnanceLaboratory) 3%) fatigue resistance is thermally switched ♦ Highcorrosion ♦ Cycle rate between its weak resistance limited by heatmartensitic state and ♦ Simple removal its high stiffness construction ♦Requires unusual austenic state. The ♦ Easy extension materials (TiNi)shape of the actuator from single nozzles ♦ The latent heat of in itsmartensitic state to pagewidth print transformation must is deformedrelative to heads be provided the austenic shape. ♦ Low voltage ♦ Highcurrent The shape change operation operation causes ejection of a ♦Requires pre- drop. stressing to distort the martensitic state LinearLinear magnetic ♦ Linear Magnetic ♦ Requires unusual ♦ IJ12 Magneticactuators include the actuators can be semiconductor Actuator LinearInduction constructed with materials such as Actuator (LIA), Linear highthrust, long soft magnetic alloys Permanent Magnet travel, and high(e.g. CoNiFe) Synchronous Actuator efficiency using ♦ Some varieties(LPMSA), Linear planar also require Reluctance semiconductor permanentmagnetic Synchronous Actuator fabrication materials such as (LRSA),Linear techniques Neodymium iron Switched Reluctance ♦ Long actuatorboron (NdFeB) Actuator (LSRA), and travel is available ♦ Requires theLinear Stepper ♦ Medium force is complex multi- Actuator (LSA).available phase drive circuitry ♦ Low voltage ♦ High current operationoperation

BASIC OPERATION MODE Description Advantages Disadvantages ExamplesActuator This is the simplest ♦ Simple operation ♦ Drop repetition ♦Thermal ink jet directly mode of operation: the ♦ No external rate isusually ♦ Piezoelectric ink pushes ink actuator directly fields requiredlimited to around 10 jet supplies sufficient ♦ Satellite drops kHz.However, this ♦ IJ01, IJ02, IJ03, kinetic energy to expel can be avoidedif is not fundamental IJ04, IJ05, IJ06, the drop. The drop drop velocityis less to the method, but is IJ07, IJ09, IJ11, must have a sufficientthan 4 m/s Related to the refill IJ12, IJ14, IJ16, velocity to overcome♦ Can be efficient, method normally IJ20, IJ22, IJ23, the surfacetension. depending upon the used IJ24, IJ25, IJ26, actuator used ♦ Allof the drop IJ27, IJ28, IJ29, kinetic energy must IJ30, IJ31, IJ32, beprovided by the IJ33, IJ34, IJ35, actuator IJ36, IJ37, IJ38, ♦ Satellitedrops IJ39, IJ40, IJ41, usually form if drop IJ42, IJ43, IJ44 velocityis greater than 4.5 m/s Proximity The drops to be ♦ Very simple print ♦Requires close ♦ Silverbrook, EP printed are selected by headfabrication can proximity between 0771 658 A2 and some manner (e.g. beused the print head and related patent thermally induced ♦ The drop theprint media or applications surface tension selection means transferroller reduction of does not need to ♦ May require two pressurized ink).provide the energy print heads printing Selected drops are required toseparate alternate rows of the separated from the ink the drop from theimage in the nozzle by nozzle ♦ Monolithic color contact with the printprint heads are medium or a transfer difficult roller. Electro- Thedrops to be ♦ Very simple print ♦ Requires very ♦ Silverbrook, EP staticpull printed are selected by head fabrication can high electrostatic0771 658 A2 and on ink some manner (e.g. be used field related patentthermally induced ♦ The drop ♦ Electrostatic field applications surfacetension selection means for small nozzle ♦ Tone-Jet reduction of doesnot need to sizes is above air pressurized ink). provide the energybreakdown Selected drops are required to separate ♦ Electrostatic fieldseparated from the ink the drop from the may attract dust in the nozzleby a nozzle strong electric field. Magnetic The drops to be ♦ Verysimple print ♦ Requires ♦ Silverbrook, EP pull on ink printed areselected by head fabrication can magnetic ink 0771 658 A2 and somemanner (e.g. be used ♦ Ink colors other related patent thermally induced♦ The drop than black are applications surface tension selection meansdifficult reduction of does not need to ♦ Requires very pressurizedink). provide the energy high magnetic fields Selected drops arerequired to separate separated from the ink the drop from the in thenozzle by a nozzle strong magnetic field acting on the magnetic ink.Shutter The actuator moves a ♦ High speed (>50 ♦ Moving parts are ♦IJ13, IJ17, IJ21 shutter to block ink kHz) operation can required flowto the nozzle. The be achieved due to ♦ Requires ink ink pressure ispulsed reduced refill time pressure modulator at a multiple of the ♦Drop timing can ♦ Friction and wear drop ejection be very accurate mustbe considered frequency. ♦ The actuator ♦ Stiction is energy can be verypossible low Shuttered The actuator moves a ♦ Actuators with ♦ Movingparts are ♦ IJ08, IJ15, IJ18, grill shutter to block ink small travelcan be required IJ19 flow through a grill to used ♦ Requires ink thenozzle. The shutter ♦ Actuators with pressure modulator movement needonly small force can be ♦ Friction and wear be equal to the width usedmust be considered of the grill holes. ♦ High speed (>50 ♦ Stiction iskHz) operation can possible be achieved Pulsed A pulsed magnetic ♦Extremely low ♦ Requires an ♦ IJ10 magnetic field attracts an ink energyoperation is external pulsed pull on ink pusher' at the drop possiblemagnetic field pusher ejection frequency. An ♦ No heat ♦ Requiresspecial actuator controls a dissipation materials for both catch, whichprevents problems the actuator and the the ink pusher from ink pushermoving when a drop is ♦ Complex not to be ejected. construction

AUXILIARY MECHANISM (APPLIED TO ALL NOZZLES) Description AdvantagesDisadvantages Examples None The actuator directly ♦ Simplicity of ♦ Dropejection ♦ Most ink jets, fires the ink drop, and construction energymust be including there is no external ♦ Simplicity of supplied bypiezoelectric and field or other operation individual nozzle thermalbubble. mechanism required. ♦ Small physical actuator ♦ IJ01, IJ02,IJ03, size IJ04, IJ05, IJ07, IJ09, IJ11, IJ12, IJ14, IJ20, IJ22, IJ23,IJ24, IJ25, IJ26, IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ35,IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Oscillating The inkpressure ♦ Oscillating ink ♦ Requires external ♦ Silverbrook, EP inkpressure oscillates, providing pressure can provide ink pressure ♦ 0771658 A2 and (including much of the drop a refill pulse, oscillatorrelated patent acoustic ejection energy. The allowing higher ♦ Inkpressure applications stimul- actuator selects which operating speedphase and amplitude ♦ IJ08, IJ13, IJ1S, ation) drops are to be fired ♦The actuators must be carefully IJ17, IJ18, IJI9, by selectively mayoperate with controlled IJ21 blocking or enabling much lower energy ♦Acoustic nozzles. The ink Acoustic lenses reflections in the inkpressure oscillation can be used to focus chamber must be may beachieved by the sound on the designed for vibrating the print nozzleshead, or preferably by an actuator in the ink supply. Media The printhead is ♦ Low power ♦ Precision ♦ Silverbrook, EP proximity placed inclose ♦ High accuracy assembly required 0771 658 A2 and proximity to theprint ♦ Simple print head ♦ Paper fibers may related patent medium.Selected construction cause problems applications drops protrude from ♦Cannot print on the print head further rough substrates than unselecteddrops, and contact the print medium. The drop soaks into the medium fastenough to cause drop separation. Transfer Drops are printed to a ♦ Highaccuracy ♦ Bulky ♦ Silverbrook, EP roller transfer roller instead ♦ Widerange of ♦ Expensive 0771 658 A2 and of straight to the print printsubstrates can ♦ Complex related patent medium. A transfer be usedconstruction applications roller can also be used ♦ Ink can be dried ♦Tektronix hot for proximity drop on the transfer roller meltpiezoelectric separation. ink jet ♦ Any of the IJ series Electro- Anelectric field is ♦ Low power ♦ Field strength ♦ Silverbrook, EP staticused to accelerate ♦ Simple print bead required for 0771 658 A2 andselected drops towards construction separation of small related patentthe print medium. drops is near or applications above air ♦ Tone-Jetbreakdown Direct A magnetic field is ♦ Low power ♦ Requires ♦Silverbrook, EP magnetic used to accelerate ♦ ♦ Simple print beadmagnetic ink 0771 658 A2 and field selected drops of construction ♦Requires strong related patent magnetic ink towards magnetic fieldapplications the print medium. Cross The print head is ♦ Does notrequire ♦ Requires external ♦ IJ06, IJ16 magnetic placed in a constantmagnetic materials magnet field magnetic field. The to be integrated in♦ Current densities Lorenz force in a the print head may be high,current carrying wire manufacturing resulting in is used to move theprocess electromigration actuator. problems Pulsed A pulsed magnetic ♦Very low power ♦ Complex print ♦ IJ10 magnetic field is used tooperation is possible head construction field cyclically attract a ♦Small print head ♦ Magnetic paddle, which pushes size materials requiredin on the ink. A small print head actuator moves a catch, whichselectively prevents the paddle from moving.

ACTUATOR AMPLIFICATION OR MODIFICATION METHOD Description AdvantagesDisadvantages Examples None No actuator ♦ Operational ♦ Many actuator ♦Thermal Bubble mechanical simplicity mechanisms have Ink jetamplification is used. insufficient travel, ♦ IJ01, IJ02, IJ06, Theactuator directly or insufficient force, IJ07, IJ16, IJ25, drives thedrop to efficiently drive IJ26 ejection process. the drop ejectionprocess Differential An actuator material ♦ Provides greater ♦ Highstresses are ♦ Piezoelectric expansion expands more on one travel in areduced involved ♦ IJ03, IJ09, IJ17, bend side than on the other. printhead area ♦ Care must be IJ18, IJ19, IJ20, actuator The expansion may betaken that the IJ21, IJ22, IJ23, thermal, piezoelectric, materials donot IJ24, IJ27, IJ29, magnetostrictive, or delaminate IJ30, IJ31, IJ32,other mechanism. The ♦ Residual bend IJ33, IJ34, IJ35, bend actuatorconverts resulting from high IJ36, IJ37, IJ38, a high force low traveltemperature or high IJ39, IJ42, IJ43, actuator mechanism to stressduring IJ44 high travel, lower formation force mechanism. Transient Atrilayer bend ♦ Very good ♦ High stresses are ♦ IJ40, IJ41 bend actuatorwhere the two temperature stability involved actuator outside layers are♦ High speed, as a ♦ Care must be identical. This cancels new drop canbe taken that the bend due to ambient fired before heat materials do nottemperature and dissipates delaminate residual stress. The ♦ Cancelsresidual actuator only responds stress of formation to transient heatingof one side or the other. Reverse The actuator loads a ♦ Better coupling♦ Fabrication ♦ IJ05, IJ11 spring spring. When the to the ink complexityactuator is turned off, ♦ High stress in the the spring releases. springThis can reverse the force/distance curve of the actuator to make itcompatible with the force/time requirements of the drop ejection.Actuator A series of thin ♦ Increased travel ♦ Increased ♦ Some stackactuators are stacked. ♦ Reduced drive fabrication piezoelectric inkjets This can be voltage complexity ♦ IJ04 appropriate where ♦ Increasedactuators require high possibility of short electric field strength,circuits due to such as electrostatic pinholes and piezoelectricactuators. Multiple Multiple smaller ♦ Increases the ♦ Actuator forces ♦IJ12, IJ13, IJ18, actuators actuators are used force available from maynot add IJ20, IJ22, IJ28, simultaneously to an actuator linearly,reducing IJ42, IJ43 move the ink. Each ♦ Multiple efficiency actuatorneed provide actuators can be only a portion of the positioned tocontrol force required. ink flow accurately Linear A linear spring isused ♦ Matches low ♦ Requires print ♦ IJ15 Spring to transform a motiontravel actuator with head area for the with small travel and highertravel spring high force into a requirements longer travel, lower ♦Non-contact force motion. method of motion transformation Coiled A bendactuator is ♦ Increases travel ♦ Generally ♦ IJ17, IJ21, IJ34, actuatorcoiled to provide ♦ Reduces chip restricted to planar IJ35 greatertravel in a area implementations reduced chip area. Planar due toextreme implementations are fabrication difficulty relatively easy to inother orientations. fabricate. Flexure A bend actuator has a ♦ Simplemeans of ♦ Care must be ♦ IJ10, IJ19,, IJ33 bend small region near theincreasing travel of taken not to exceed actuator fixture point, which abend actuator the elastic limit in flexes much more the flexure areareadily than the ♦ Stress remainder of the distribution is veryactuator. The actuator uneven flexing is effectively ♦ Difficult toconverted from an accurately model even coiling to an with finiteelement angular bend, resulting analysis in greater travel of theactuator tip. Catch The actuator controls a ♦ Very low ♦ Complex ♦ IJ10small catch. The catch actuator energy construction either enables or ♦Very small ♦ Requires external disables movement of actuator size forcean ink pusher that is ♦ Unsuitable for controlled in a bulk pigmentedinks manner. Gears Gears can be used to ♦ Low force, low ♦ Moving partsare ♦ IJ13 increase travel at the travel actuators can required expenseof duration. be used ♦ Several actuator Circular gears, rack ♦ Can befabricated cycles are required and pinion, ratchets, using standard ♦More complex and other gearing surface MEMS drive electronics methodscan be used. processes ♦ Complex construction ♦ Friction, friction, andwear are possible Buckle plate A buckle plate can be ♦ Very fast ♦ Muststay within ♦ S. Hirata et al, used to change a slow movement elasticlimits of the “An Ink-jet Head actuator into a fast achievable materialsfor long Using Diaphragm motion. It can also device life Microactuator”,convert a high force, ♦ High stresses Proc. IEEE MEMS, low travelactuator involved Feb. 1996, pp 418- into a high travel, ♦ Generallyhigh 423. medium force motion. power requirement ♦ IJ18, IJ27 Tapered Atapered magnetic ♦ Linearizes the ♦ Complex ♦ IJ14 magnetic pole canincrease magnetic construction pole travel at the expense force/distancecurve of force. Lever A lever and fulcrum is ♦ Matches low ♦ High stress♦ IJ32, IJ36, IJ37 used to transform a travel actuator with around thefulcrum motion with small higher travel travel and high forcerequirements into a motion with ♦ Fulcrum area has longer travel and nolinear movement, lower force. The lever and can be used for can alsoreverse the a fluid seal direction of travel. Rotary The actuator is ♦High mechanical ♦ Complex ♦ IJ28 impeller connected to a rotaryadvantage construction impeller. A small ♦ The ratio of force ♦Unsuitable for angular deflection of to travel of the pigmented inks theactuator results in actuator can be a rotation of the matched to theimpeller vanes, which nozzle requirements push the ink against byvarying the stationary vanes and number of impeller out of the nozzle.vanes Acoustic A refractive or ♦ No moving parts ♦ Large area ♦ 1993Hadimioglu lens diffractive (e.g. zone required et al, EUP 550,192plate) acoustic lens is ♦ Only relevant for ♦ 1993 Elrod et al, used toconcentrate acoustic ink jets EUP 572,220 sound waves. Sharp A sharppoint is used ♦ Simple ♦ Difficult to ♦ Tone-jet conductive toconcentrate an construction fabricate using point electrostatic field.standard VLSI processes for a surface ejecting ink- jet ♦ Only relevantfor electrostatic ink jets

ACTUATOR MOTION Description Advantages Disadvantages Examples Volume Thevolume of the ♦ Simple ♦ High energy is ♦ Hewlett-Packard expansionactuator changes, construction in the typically required to Thermal Inkjet pushing the ink in all case of thermal ink achieve volume ♦ CanonBubblejet directions. jet expansion. This leads to thermal stress,cavitation, and kogation in thermal ink jet implementations Linear, Theactuator moves in ♦ Efficient ♦ High fabrication ♦ IJ01, IJ02, IJ04,normal to a direction normal to coupling to ink complexity may be IJ07,IJ11, IJ14 chip surface the print head surface. drops ejected requiredto achieve The nozzle is typically normal to the perpendicular in theline of surface motion movement. Parallel to The actuator moves ♦Suitable for ♦ Fabrication ♦ IJ12, IJ13, IJ15, chip surface parallel tothe print planar fabrication complexity IJ33,, IJ34, IJ35, head surface.Drop ♦ Friction IJ36 ejection may still be ♦ Stiction normal to thesurface. Membrane An actuator with a ♦ The effective ♦ Fabrication ♦1982 Howkins push high force but small area of the actuator complexityU.S. Pat. No. 4,459,601 area is used to push a becomes the ♦ Actuatorsize stiff membrane that is membrane area ♦ Difficulty of in contactwith the ink. integration in a VLSI process Rotary The actuator causes ♦Rotary levers ♦ Device ♦ IJ05, IJ08, IJ13, the rotation of some may beused to complexity IJ28 element, such a grill or increase travel ♦ Mayhave impeller ♦ Small chip area friction at a pivot requirements pointBend The actuator bends ♦ A very small ♦ Requires the ♦ 1970 Kyser et alwhen energized. This change in actuator to be made U.S. Pat. No.3,946,398 may be due to dimensions can be from at least two ♦ 1973Stemme differential thermal converted to a large distinct layers, or toU.S. Pat. No. 3,747,120 expansion, motion. have a thermal ♦ IJ03, IJ09,IJ10, piezoelectric difference across the IJ19, IJ23, IJ24, expansion,actuator IJ25, IJ29, IJ30, magnetostriction, or IJ31, IJ33, IJ34, otherform of relative IJ35 dimensional change. Swivel The actuator swivels ♦Allows operation ♦ Inefficient ♦ IJ06 around a central pivot. where thenet linear coupling to the ink This motion is suitable force on thepaddle motion where there are is zero opposite forces ♦ Small chip areaapplied to opposite requirements sides of the paddle, e.g. Lorenz force.Straighten The actuator is ♦ Can be used with ♦ Requires careful ♦ IJ26,IJ32 normally bent, and shape memory balance of stresses straightenswhen alloys where the to ensure that the energized. austenic phase isquiescent bend is planar accurate Double The actuator bends in ♦ Oneactuator can ♦ Difficult to make ♦ IJ36, IJ37, IJ38 bend one directionwhen be used to power the drops ejected by one element is two nozzles.both bend directions energized, and bends ♦ Reduced chip identical. theother way when size. ♦ A small another element is ♦ Not sensitive toefficiency loss energized. ambient temperature compared to equivalentsingle bend actuators. Shear Energizing the ♦ Can increase the ♦ Notreadily ♦ 1985 Fishbeck actuator causes a shear effective travel ofapplicable to other U.S. Pat. No. 4,584,590 motion in the actuatorpiezoeledtric actuator material. actuators mechanisms Radial con- Theactuator squeezes ♦ Relatively easy ♦ High force ♦ 1970 Zoltan U.S. Pat.No. striction an ink reservoir, to fabricate single required 3,683,212forcing ink from a nozzles from glass ♦ Inefficient constricted nozzle.tubing as ♦ Difficult to macroscopic integrate with VLSI structuresprocesses Coil/uncoil A coiled actuator ♦ Easy to fabricate ♦ Difficultto ♦ IJ17, IJ21, IJ34, uncoils or coils more as a planar VLSI fabricatefor non- IJ35 tightly. The motion of. process planar devices the freeend of the ♦ Small area ♦ Poor out-of-plane actuator ejects the ink.required, therefore stiffness low cost Bow The actuator bows (or ♦ Canincrease the ♦ Maximum travel ♦ IJ16, IJ18, IJ27 buckles) in the middlespeed of travel is constrained when energized. ♦ Mechanically ♦ Highforce rigid required Push-Pull Two actuators control ♦ The structure is♦ Not readily ♦ IJ18 a shutter. One actuator pinned at both ends,suitable for ink jets pulls the shutter, and so has a high out-of- whichdirectly push the other pushes it. plane rigidity the ink Curl A set ofactuators curl ♦ Good fluid flow ♦ Design ♦ IJ20, IJ42 inwards inwardsto reduce the to the region behind complexity volume of ink that theactuator they enclose. increases efficiency Curl A set of actuators curl♦ Relatively simple ♦ Relatively large ♦ IJ43 outwards outwards,pressurizing construction chip area ink in a chamber surrounding theactuators, and expelling ink from a nozzle in the chamber. Iris Multiplevanes enclose ♦ High efficiency ♦ High fabrication ♦ IJ22 a volume ofink. These ♦ Small chip area complexity simultaneously rotate, ♦ Notsuitable for reducing the volume pigmented inks between the vanes.Acoustic The actuator vibrates ♦ The actuator can ♦ Large area ♦ 1993Hadimioglu vibration at a high frequency. be physically distant requiredfor et al, EUP 550,192 from the ink efficient operation ♦ 1993 Elrod etal, at useful frequencies EUP 572,220 ♦ Acoustic coupling and crosstalk♦ Complex drive circuitry ♦ Poor control of drop volume and positionNone In various ink jet ♦ No moving pans ♦ Various other ♦ Silverbrcok,EP designs the actuator tradeoffs are 0771 658 A2 and does not move.required to related patent eliminate moving applications parts ♦Tone-jet

NOZZLE REFILL METHOD Description Advantages Disadvantages ExamplesSurface This is the normal way ♦ Fabrication ♦ Low speed ♦ Thermal inkjet tension that ink jets are simplicity ♦ Surface tension ♦Piezoelectric ink refilled. After the ♦ Operational force relatively jetactuator is energized, simplicity small compared to ♦ IJ01-IJ07; IJ10-it typically returns actuator force IJ14, IJ16, IJ20, rapidly to itsnormal ♦ Long refill time IJ22-IJ45 position. This rapid usuallydominates return sucks in air the total repetition through the nozzlerate opening. The ink surface tension at the nozzle then exerts a smallforce restoring the meniscus to a minimum area. This force refills thenozzle. Shuttered Ink to the nozzle ♦ High speed ♦ Requires ♦ IJ08,IJ13, IJ15, oscillating chamber is provided at ♦ Low actuator common inkIJ17, IJ18, IJ19, ink pressure a pressure that energy, as the pressureoscillator IJ21 oscillates at twice the actuator need only ♦ May not bedrop ejection open or close the suitable for frequency. When a shutter,instead of pigmented inks drop is to be ejected, ejecting the ink dropthe shutter is opened for 3 half cycles: drop ejection, actuator return,and refill. The shutter is then closed to prevent the nozzle chamberemptying during the next negative pressure cycle. Refill After the main♦ High speed, as ♦ Requires two ♦ IJ09 actuator actuator has ejected athe nozzle is independent drop a second (refill) actively refilledactuators per nozzle actuator is energized. The refill actuator pushesink into the nozzle chamber. The refill actuator returns slowly, toprevent its return from emptying the chamber again. Positive ink The inkis held a slight ♦ High refill rate, ♦ Surface spill ♦ Silverbrook, EPpressure positive pressure. therefore a high must be prevented 0771 658A2 and After the ink drop is drop repetition rate ♦ Highly relatedpatent ejected, the nozzle is possible hydrophobic print applicationschamber fills quickly head surfaces are ♦ Alternative for:, as surfacetension and required IJ01-IJ07, IJ10-IJ14, ink pressure both IJ16, IJ20,IJ22-IJ45 operate to refill the nozzle.

METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Description AdvantagesDisadvantages Examples Long inlet The ink inlet channel ♦ Designsimplicity ♦ Restricts refill ♦ Thermal ink jet channel to the nozzlechamber ♦ Operational rate ♦ Piezoelectric ink is made long andsimplicity ♦ May result in a jet relatively narrow, ♦ Reduces relativelylarge chip ♦ IJ42, IJ43 relying on viscous crosstalk area drag to reduceinlet ♦ Only partially back-flow. effective Positive ink The ink isunder a ♦ Drop selection ♦ Requires a ♦ Silverbrook, EP pressurepositive pressure, so and separation method (such as a 0771 658 A2 andthat in the quiescent forces can be nozzle rim or related patent statesome of the ink reduced effective applications drop already protrudes ♦Fast refill time hydrophobizing, or ♦ Possible from the nozzle. both) toprevent operation of the This reduces the flooding of the following:IJ01- pressure in the nozzle ejection surface of IJ07, IJ09-IJ12,chamber which is the print head. IJ14, IJ16, IJ20, required to eject aIJ22,, IJ23-IJ34, certain volume of ink. IJ36-IJ41, IJ44 The reductionin chamber pressure results in a reduction in ink pushed out through theinlet. Baffle One or more baffles ♦ The refill rate is ♦ Design ♦ HPThermal Ink are placed in the inlet not as restricted as complexity Jetink flow. When the the long inlet ♦ May increase ♦ Tektronix actuator isenergized, method. fabrication piezoelectric ink jet the rapid ink ♦Reduces complexity (e.g. movement creates crosstalk Tektronix hot melteddies which restrict Piezoelectric print the flow through the heads).inlet. The slower refill process is unrestricted, and does not result ineddies. Flexible flap In this method recently ♦ Significantly ♦ Notapplicable to ♦ Canon restricts disclosed by Canon, reduces back-flowmost ink jet inlet the expanding actuator for edge-shooterconfigurations (bubble) pushes on a thermal ink jet ♦ Increased flexibleflap that devices fabrication restricts the inlet. complexity ♦Inelastic deformation of polymer flap results in creep over extended useInlet filter A filter is located ♦ Additional ♦ Restricts refill ♦ IJ04,IJ12, IJ24, between the ink inlet advantage of ink rate IJ27, IJ29, IJ30and the nozzle filtration ♦ May result in chamber. The filter ♦ Inkfilter may be complex has a multitude of fabricated with no constructionsmall holes or slots, additional process restricting ink flow. steps Thefilter also removes particles which may block the nozzle. Small inletThe ink inlet channel ♦ Design simplicity ♦ Restricts refill ♦ IJ02,IJ37, IJ44 compared to the nozzle chamber rate to nozzle has asubstantially ♦ May result in a smaller cross section relatively largechip than that of the nozzle, area resulting in easier ink ♦ Onlypartially egress out of the effective nozzle than out of the inlet.Inlet shutter A secondary actuator ♦ Increases speed ♦ Requires separate♦ IJ09 controls the position of of the ink-jet print refill actuator anda shutter, closing off head operation drive circuit the ink inlet whenthe main actuator is energized. The inlet is The method avoids the ♦Back-flow ♦ Requires careful ♦ IJ01, IJ03, IJ05, located problem ofinlet back- problem is design to minimize IJ06, IJ07, IJ10, behind theflow by arranging the eliminated the negative IJ11, IJ14, IJ16,ink-pushing ink-pushing surface of pressure behind the IJ22, IJ23, IJ25,surface the actuator between paddle IJ28, IJ31, IJ32, the inlet and theIJ33, IJ34, IJ35, nozzle. IJ36, IJ39, IJ40, IJ41 Part of the Theactuator and a ♦ Significant ♦ Small increase in ♦ IJ07, IJ20, IJ26,actuator wall of the ink reductions in back- fabrication IJ38 moves tochamber are arranged flow can be complexity shut off the so that themotion of achieved inlet the actuator closes off ♦ Compact designs theinlet. possible Nozzle In some configurations ♦ Ink back-flow ♦ Nonerelated to ♦ Silverbrook, EP actuator of ink jet, there is no problem isink back-flow on 0771 658 A2 and does not expansion or eliminatedactuation related patent result in ink movement of an applicationsback-flow actuator which may ♦ Valve-jet cause ink back-flow ♦ Tone-jetthrough the inlet.

NOZZLE CLEARING METHOD Description Advantages Disadvantages ExamplesNormal All of the nozzles are ♦ No added ♦ May not be ♦ Most ink jetsnozzle firing fired periodically, complexity on the sufficient tosystems before the ink has a print head displace dried ink ♦ IJ01, IJ02,IJ03, chance to dry. When IJ04, IJ05, IJ06, not in use the nozzles IJ07,IJ09, IJ10, are sealed (capped) IJ11, IJ12, IJ14, against air. IJ16,IJ20, IJ22, The nozzle firing is IJ23, IJ24, IJ25, usually performedIJ26, IJ27, IJ28, during a special IJ29, IJ30, 1131, clearing cycle,after IJ32, IJ33, IJ34, first moving the print IJ36, IJ37, IJ38, head toa cleaning IJ39, IJ40,, IJ41, station. IJ42, IJ43, IJ44,, JJ45 Extra Insystems which heat ♦ Can be highly ♦ Requires higher ♦ Silverbrook, EPpower to the ink, but do not boil effective if the drive voltage for0771 658 A2 and ink heater it under normal heater is adjacent toclearing related patent situations, nozzle the nozzle ♦ May requireapplications clearing can be larger drive achieved by over- transistorspowering the heater and boiling ink at the nozzle. Rapid The actuator isfired in ♦ Does not require ♦ Effectiveness ♦ May be used successionrapid succession. In extra drive circuits depends with: IJ01, IJ02, ofactuator some configurations, on the print head substantially upon IJ03,IJ04, IJ05, pulses this may cause heat ♦ Can be readily theconfiguration of IJ06, IJ07, IJ09, build-up at the nozzle controlled andthe ink jet nozzle IJ10, IJ11, IJ14, which boils the ink, initiated bydigital IJ16, IJ20, IJ22, clearing the nozzle. In logic IJ23, IJ24,IJ25, other situations, it may IJ27, IJ28, IJ29, cause sufficient IJ30,IJ31, IJ32, vibrations to dislodge IJ33, IJ34, IJ36, clogged nozzles.IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44, IJ45 Extra Where anactuator is ♦ A simple ♦ Not suitable ♦ May be used power to notnormally driven to solution where where there is a with: IJ03, IJ09, inkpushing the limit of its motion, applicable hard limit to IJ16, IJ20,IJ23, actuator nozzle clearing may be actuator movement IJ24, IJ25,IJ27, assisted by providing IJ29, IJ30, IJ31, an enhanced drive IJ32,IJ39, IJ40, signal to the actuator. IJ41, IJ42, IJ43, IJ44, IJ45Acoustic An ultrasonic wave is ♦ A high nozzle ♦ High ♦ IJ08, IJ13,IJ15, resonance applied to the ink clearing capability implementationcost IJ17, IJ18, IJ19, chamber. This wave is can be achieved if systemdoes not IJ21 of an appropriate ♦ May be already include an amplitudeand implemented at very acoustic actuator frequency to cause low cost insystems sufficient force at the which already nozzle to clear includeacoustic blockages. This is actuators easiest to achieve if theultrasonic wave is at a resonant frequency of the ink cavity. Nozzle Amicrofabricated ♦ Can clear ♦ Accurate ♦ Silverbrook, EP clearing plateis pushed against severely clogged mechanical 0771 658 A2 and plate thenozzles. The plate nozzles alignment is related patent has a post forevery required applications nozzle. A post moves ♦ Moving parts arethrough each nozzle, required displacing dried ink. ♦ There is risk ofdamage to the nozzles ♦ Accurate fabrication is required Ink Thepressure of the ink ♦ May be effective ♦ Requires ♦ May be used pressureis temporarily where other pressure pump or with all IJ series ink pulseincreased so that ink methods cannot be other pressure jets streams fromall of the used actuator nozzles. This may be ♦ Expensive used inconjunction ♦ Wasteful of ink with actuator energizing. Print head Aflexible ‘blade’ is ♦ Effective for ♦ Difficult to use if ♦ Many ink jetwiper wiped across the print planar print head print head surface issystems head surface. The surfaces non-planar or very blade is usually ♦low cost fragile fabricated from a ♦ Requires flexible polymer, e.g.mechanical parts rubber or synthetic ♦ Blade can wear elastomer. out inhigh volume print systems Separate A separate heater is ♦ Can beeffective ♦ Fabrication ♦ Can be used with ink boiling provided at thenozzle where other nozzle complexity many IJ series ink heater althoughthe normal clearing methods jets drop ejection cannot be used mechanismdoes not ♦ Can be require it. The heaters implemented at no do notrequire additional cost in individual drive some ink jet circuits, asmany configurations nozzles can be cleared simultaneously, and noimaging is required.

NOZZLE PLATE CONSTRUCTION Description Advantages Disadvantages ExamplesElectro- A nozzle plate is ♦ Fabrication ♦ High ♦ Hewlett Packard formedseparately fabricated simplicity temperatures and Thermal Ink jet nickelfrom electroformed pressures are nickel, and bonded to required to bondthe print head chip. nozzle plate ♦ Minimum thickness constraints ♦Differential thermal expansion Laser Individual nozzle ♦ No masks ♦ Eachhole must ♦ Canon Bubblejet ablated or holes are ablated by an requiredbe individually ♦ 1988 Sercel et drilled intense UV laser in a ♦ Can bequite fast formed al., SPIE, Vol. 998 polymer nozzle plate, which is ♦Some control ♦ Special Excimer Beam typically a polymer over nozzleprofile equipment required Applications, pp. such as polyimide or ispossible ♦ Slow where there 76-83 polysulphone ♦ Equipment are manythousands ♦ 1993 Watanabe required is relatively of nozzles per print etal., U.S. Pat. No. low cost head 5,208,604 ♦ May produce thin burrs atexit holes Silicon A separate nozzle ♦ High accuracy is ♦ Two part ♦ K.Bean, IEEE micro- plate is attainable construction Transactions onmachined micromachined from ♦ High cost Electron Devices, single crystalsilicon, ♦ Requires Vol. ED-25, No. 10, and bonded to the precisionalignment 1978, pp 1185-1195 print head wafer. ♦ Nozzles may be ♦ Xerox1990 clogged by adhesive Hawkins et al., U.S. Pat. No. 4,899,181 GlassFine glass capillaries ♦ No expensive ♦ Very small ♦ 1970 Zlotan U.S.Pat. No. capillaries are drawn from glass equipment required nozzlesizes are 3,683,212 tubing. This method ♦ Simple to make difficult toform has been used for single nozzles ♦ Not suited for making individualmass production nozzles, but is difficult to use for bulk manufacturingof print heads with thousands of nozzles. Monolithic, The nozzle plateis ♦ High accuracy ♦ Requires ♦ Silverbrook, EP surface deposited as alayer (<1 μm) sacrificial layer 0771 658 A2 and micro- using standardVLSI ♦ Monolithic under the nozzle related patent machined depositiontechniques. ♦ Low cost plate to form the applications using VLSI Nozzlesare etched in ♦ Existing nozzle chamber ♦ IJ01, IJ02, IJ04, litho- thenozzle plate using processes can be ♦ Surface may be IJ11, IJ12, IJ17,graphic VLSI lithography and used fragile to the touch IJ18, IJ20, IJ22,processes etching. IJ24, IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34,IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Monolithic, Thenozzle plate is a ♦ High accuracy ♦ Requires long ♦ IJ03, IJ05, IJ06,etched buried etch stop in the (<1 μm) etch times IJ07, IJ08, IJ09,through wafer. Nozzle ♦ Monolithic ♦ Requires a IJ10, IJ13, IJ14,substrate chambers are etched in ♦ Low cost support wafer IJ15, IJ16,IJ19, the front of the wafer, ♦ No differential IJ21, IJ23, IJ25, andthe wafer is expansion IJ26 thinned from the back side. Nozzles are thenetched in the etch stop layer. No nozzle Various methods have ♦ Nonozzles to ♦ Difficult to ♦ Ricoh 1995 plate been tried to eliminatebecome clogged control drop Sekiya et al U.S. Pat. No. the nozzlesentirely, to position accurately 5,412,413 prevent nozzle ♦ Crosstalk ♦1993 Hadimioglu clogging. These problems et al EUP 550,192 includethermal bubble ♦ 1993 Elrod et al mechanisms and EUP 572,220 acousticlens mechanisms Trough Each drop ejector has ♦ Reduced ♦ Drop firing ♦IJ35 a trough through manufacturing direction is sensitive which apaddle moves. complexity to wicking. There is no nozzle ♦ Monolithicplate. Nozzle slit The elimination of ♦ No nozzles to ♦ Difficult to ♦1989 Saito et al instead of nozzle holes and become clogged control dropU.S. Pat. No. 4,799,068 individual replacement by a slit positionaccurately nozzles encompassing many ♦ Crosstalk actuator positionsproblems reduces nozzle clogging, but increases crosstalk due to inksurface waves

DROP EJECTION DIRECTION Description Advantages Disadvantages ExamplesEdge Ink flow is along the ♦ Simple ♦ Nozzles limited ♦ Canon Bubblejet(‘edge surface of the chip, construction to edge 1979 Endo et al GBshooter’) and ink drops are ♦ No silicon ♦ High resolution patent2,007,162 ejected from the chip etching required is difficult ♦ Xeroxheater-in- edge. ♦ Good heat ♦ Fast color pit 1990 Hawkins et sinkingvia substrate printing requires al U.S. Pat. No. 4,899,181 ♦Mechanically one print head per ♦ Tone-jet strong color ♦ Ease of chiphanding Surface Ink flow is along the ♦ No bulk silicon ♦ Maximum ink ♦Hewlett-Packard (‘roof surface of the chip, etching required flow isseverely TIJ 1982 Vaught et shooter’) and ink drops are ♦ Silicon canmake restricted al U.S. Pat. No. 4,490,728 ejected from the chip aneffective heat ♦ IJ02, IJ11, IJ12, surface, normal to the sink IJ20,IJ22 plane of the chip. ♦ Mechanical strength Through Ink flow isthrough the ♦ High ink flow ♦ Requires bulk ♦ Silverbrook, EP chip,chip, and ink drops are ♦ Suitable for silicon etching 0771 658 A2 andforward ejected from the front pagewidth print related patent (‘upsurface of the chip. heads applications shooter’) ♦ High nozzle ♦ IJ04,IJ17, IJ18, packing density IJ24, IJ27-IJ45 therefore low manufacturingcost Through Ink flow is through the ♦ High ink flow ♦ Requires wafer ♦IJ01, IJ03, IJ05, chip, chip, and ink drops are ♦ Suitable for thinningIJ06, IJ07, IJ08, reverse ejected from the rear pagewidth print ♦Requires special IJ09, IJ10, IJ13, (‘down surface of the chip. headshandling during IJ14, IJ15, IJ16, shooter’) ♦ High nozzle manufactureIJ19, IJ21, IJ23, packing density IJ25, IJ26 therefore low manufacturingcost Through Ink flow is through the ♦ Suitable for ♦ Pagewidth print ♦Epson Stylus actuator actuator, which is not piezoelectric print headsrequire ♦ Tektronix hot fabricated as part of heads several thousandmelt piezoelectric the same substrate as connections to drive ink jetsthe drive transistors. circuits ♦ Cannot be manufactured in standardCMOS fabs ♦ Complex assembly required

INK TYPE Description Advantages Disadvantages Examples Aqueous, Waterbased ink which ♦ Environmentally ♦ Slow drying ♦ Most existing ink dyetypically contains: friendly ♦ Corrosive jets water, dye, surfactant, ♦No odor ♦ Bleeds on paper ♦ All IJ series ink humectant, and ♦ May jetsbiocide. strikethrough ♦ Silverbrook, EP Modern ink dyes have ♦ Cocklespaper 0771 658 A2 and high water-fastness, related patent light fastnessapplications Aqueous, Water based ink which ♦ Environmentaily ♦ Slowdrying ♦ IJ02, IJ04, IJ21, pigment typically contains: friendly ♦Corrosive IJ26, IJ27, IJ30 water, pigment, ♦ No odor ♦ Pigment may ♦Silverbrook, EP surfactant, humectant, ♦ Reduced bleed clog nozzles 0771658 A2 and and biocide. ♦ Reduced wicking ♦ Pigment may related patentPigments have an ♦ Reduced clog actuator applications advantage inreduced strikethrough mechanisms ♦ Piezoelectric ink- bleed, wicking and♦ Cockles paper jets strikethrough. ♦ Thermal ink jets (with significantrestrictions) Methyl MEK is a highly ♦ Very fast drying ♦ Odorous ♦ AllIJ series ink Ethyl volatile solvent used ♦ Prints on various ♦Flammable jets Ketone for industrial printing substrates such as (MEK)on difficult surfaces metals and plastics such as aluminum cans. AlcoholAlcohol based inks ♦ Fast drying ♦ Slight odor ♦ All IJ series ink(ethanol, 2- can be used where the ♦ Operates at sub- ♦ Flammable jetsbutanol, printer must operate at freezing and others) temperatures belowtemperatures the freezing point of ♦ Reduced paper water. An example ofcockle this is in-camera ♦ Low cost consumer photographic printing.Phase The ink is solid at ♦ No drying time- ♦ High viscosity ♦ Tektronixhot change room temperature, and ink instantly freezes ♦ Printed inkmelt piezoelectric (hot melt) is melted in the print on the print mediumtypically has a ink jets head before jetting. ♦ Almost any print ‘waxy’feel ♦ 1989 Nowak Hot melt inks are medium can be used ♦ Printed pagesU.S. Pat. No. 4,820,346 usually wax based, ♦ No paper cockle may ‘block’♦ All IJ series ink with a melting point occurs ♦ Ink temperature jetsaround 80° C. After ♦ No wicking may be above the jetting the inkfreezes occurs curie point of almost instantly upon ♦ No bleed occurspermanent magnets contacting the print ♦ No strikethrough ♦ Ink heatersmedium or a transfer occurs consume power roller. ♦ Long warm-up timeOil Oil based inks are ♦ High solubility ♦ High viscosity: ♦ All IJseries ink extensively used in medium for some this is a significantjets offset printing. They dyes limitation for use in have advantages in♦ Does not cockle ink jets, which improved paper usually require acharacteristics on ♦ Does not wick low viscosity. Some paper (especiallyno through paper short chain and wicking or cockle). multi-branched oilsOil soluble dies and have a sufficiently pigments are required. lowviscosity. ♦ Slow drying Micro- A microemulsion is a ♦ Stops ink bleed ♦Viscosity higher ♦ All IJ series in emulsion stable, self forming ♦ Highdye than water jets emulsion of oil, water, solubility ♦ Cost isslightly and surfactant. The ♦ Water, oil, and higher than watercharacteristic drop size amphiphilic soluble based ink is less than 100nm, dies can be used ♦ High surfactant and is determined by ♦ Canstabilize concentration the preferred curvature pigment required (aroundof the surfactant. suspensions 5%)

What is claimed is:
 1. An ink jet print head comprising: (a) a nozzlechamber having walls and an ink ejection port at one of said walls; (b)a fixed electric coil located within the chamber or within one of saidwalls of said chamber; and (c) a movable plate, in which there isembedded another electric coil, located close to said fixed electriccoil such that when a current passing through said coils is altered, themovable plate moves towards or away from said fixed electric coil andwherein said movement is utilized to eject ink from said nozzle chambervia said ink ejection port.
 2. An ink jet print head as claimed in claim1 further comprising: a sprint connected to said movable plate whereinsaid movable plate goes from a quiescent position to a spring loadedposition upon activation of said coils and upon deactivation of saidcoils said spring causes said movable coil to return to its quiescentposition and to thereby eject ink from said ink ejection port.
 3. An inkjet print head as claimed in claim 2 wherein said spring comprises atorsional spring attached to said movable coil.
 4. An ink jet print headas claimed in claim 3 wherein a conductive strip is connected to saidcoils and is located within said torsional spring.
 5. An ink jet printhead as claimed in claim 1 wherein said electric coil of said movableplate comprises a stacked multi level spiral of conductive material. 6.An ink jet print head as claimed in claim 5 wherein said stackedconductive material is interconnected at a central axial point of saidspiral.
 7. An ink jet print head as claimed in claim 1 wherein saidcoils are electrically connected together to form a combined circuit. 8.An ink jet print head as claimed in any previous claim wherein saidcoils comprise substantially copper.
 9. An ink jet print head as claimedin claim 1 wherein said coils are formed by a damascene constructionprocess.
 10. An ink jet print head as claimed in claim 1 wherein saidnozzle is constructed utilizing a sacrificial etch to release astructure of said movable coil.
 11. An ink jet print head as claimed inclaim 10 wherein an outer surface of said nozzle chamber includes aseries of small etched holes for etching of any sacrificial layerutilized in the construction of said ink jet print head.
 12. An ink jetprint head as claimed in claim 1 wherein said nozzle chamber includes aseries of slots within the walls of said nozzle chamber so as to allow asupply of ink to said nozzle chamber.
 13. A method of ejecting ink froma nozzle chamber utilizing electro-magnetic forces between two coilsembedded into plates to cause movement of at least one of said plates,the movement further causing consequential ejection of ink from saidnozzle chamber.
 14. A method of ejecting ink as claimed in claim 13wherein said plates comprise a movable plate and a fixed plate, saidmovable plate further being connected to a spring which upon saidmovement of said movable plate, stores energy such that upondeactivation of a current through said coils, said spring releases itsstored energy to thereby cause movement of said movable plate so as tocause ejection of ink from said nozzle.